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About this Tool
Base64 Encoder & Decoder — Free Online Tool
Encode any text to Base64 or decode Base64 strings back to plain text instantly. This free online Base64 converter is essential for developers working with APIs, JWT tokens, email encoding (MIME), data URIs, and authentication headers.
The swap button lets you switch between encode and decode mode instantly. Supports UTF-8 encoding for full Unicode character support including emojis, accented characters, and CJK text.
Common use cases: encoding API keys, decoding JWT payloads, creating data URIs for inline images, debugging HTTP authentication headers. Stateless — your data never touches our servers.
Live Examples
Example 1 — Encode plain text
Input: Hello, World!
Output: SGVsbG8sIFdvcmxkIQ==
Example 2 — Encode a JSON payload
Input: {"user":"admin","role":"editor"}
Output: eyJ1c2VyIjoiYWRtaW4iLCJyb2xlIjoiZWRpdG9yIn0=
This is exactly how JWT payloads are encoded (with URL-safe Base64).
Example 3 — Decode an HTTP Basic Auth header
Input (Base64): dXNlcjpwYXNzd29yZDEyMw==
Output: user:password123
HTTP Basic Authentication encodes username:password as Base64. Use decode mode to inspect auth headers.
Example 4 — Unicode / emoji support
Input: Merhaba dünya 🌍
Output: TWVyaGFiYSBkw7xueWEg8J+MjQ==
Full UTF-8 support means accented characters, CJK text, and emojis encode/decode correctly.
Technical Details
- Encoding follows RFC 4648 (standard Base64 alphabet with
+,/, and=padding) - Input text is encoded as UTF-8 bytes before Base64 conversion
- Decoding trims whitespace and handles both padded and unpadded input
- Does not produce URL-safe Base64 (
-and_) — use URL Encoder for that
When to Use
- Inspecting or crafting HTTP
Authorization: Basicheaders - Encoding data for embedding in JSON, XML, or HTML (
data:URIs) - Debugging JWT token segments (header + payload are Base64-encoded)
- Embedding small files as inline data in CSS or HTML
When Not to Use
- Encryption: Base64 is encoding, not encryption — anyone can decode it
- Large files: Base64 adds ~33% overhead; use proper file transfer instead
- URL parameters: Standard Base64 contains
+and/which break URLs — use URL encoding
Related Tools: JWT Decoder · URL Encoder · Hash Generator